This invention relates to a power transmission system and more particularly to an arrangement for driving a shaft from the aligned output shafts of an internal combustion engine.
In many instances, it is desirable to drive a shaft from an engine output shaft at a point other than at the end of the engine output shaft. It is particularly desirable if the engine is provided with separate output shafts so as to decrease the overall length of the individual output shafts and to drive the driven shaft from the adjacent ends of the engine output shafts. Such an arrangement has a number of advantages but it also presents certain problems.
For example, when the engine is split and has two separate engine output shafts, even though the output shafts are maintained in a coaxial relationship, vibrations and flexures can cause the output shafts to assume a somewhat angular relationship to each other. With conventional driving arrangements, this can present significant problems.
It is, therefore, a principal object of this invention to provide an improved arrangement for driving a shaft from adjacent ends of a pair of engine output shafts and wherein the drive accommodates some angular movement between the engine output shafts.
Although it is desirable to accommodate angular movement between the engine output shafts for the purposes aforenoted, the joint which accommodates the angular movement must also be strong enough to permit full power transmission. It is, therefore, a still further object of this invention to provide an improved joint arrangement for driving a shaft from the adjacent ends of a pair of engine output shafts wherein the joint accommodates angular movement between the engine output shafts but still is capable of transmitting large amounts of power.
There are many instances when it is desirable to provide a drive from an engine wherein the shaft driven is driven off of a split engine output shaft. For example, it is conventional in snowmobile construction to mount the driving internal combustion engine so that its output shaft rotates about an axis that extends transversely to the longitudinal center line of the snowmobile. The engine output shaft is then coupled through a variable transmission, which may include a centrifugal clutch, to the drive belt. Due to the substantial width of the drive belts of the snowmobile, it has heretofore, been the practice to drive the variable transmission off one end of the engine output shaft. However, this has several disadvantages.
In the first instance, if the engine output shaft also drives the variable transmission, side loadings on the engine output shaft will be generated due to the inherent operation of the variable transmission. This can place undue wear on the engine output shaft.
In addition, when the variable transmission and a centrifugal clutch is placed on the end of the engine output shaft, then the overall drive package becomes quite large. This is a particular problem when a multiple cylinder engine is employed since the engine itself may be quite long. In addition, driving the transmission off one end of the engine output shaft, even if the transmission is driven through an intermediate shaft, can put substantial torsional loading on the output shaft of the engine.
It is, therefore, a further object of this invention to provide an improved power transmission system for a snowmobile.
It is a further object of this invention to provide a power transmission system for a snowmobile wherein the engine and transmission package may be kept quite compact even when multiple cylinder engines are employed.
It is a further object of the invention to provide an improved arrangement for driving an intermediate shaft which drives a variable transmission for a snowmobile drive from an engine without placing large torsional stresses on the engine output shaft.